1. Field of the Invention
The present invention relates to gas-operated firearms and more particularly to improved gas-operated firearms in which the gas port is located in the forward portion of the catridgechamber and in which the bolt is locked in its breech-closing position until the pressure of the gas generated by the detonation of a cartridge drops to a very low level or practically zero (gauge).
2. Description of the Prior Art
Gas-operated firearms are well known in the prior art. In all of the successful gas-operated firearms of which I am aware, however, the operating gas pressure is derived from a port located somewhere along the barrel beyond the mouth of the cartridge-containing chamber portion of the barrel. This conventional gas port location, i.e., along the barrel, has the advantage of providing operating gas pressures which are lower than the very high pressures initially generated in the cartridgecontaining chamber portion of the barrel bore immediately after the cartridge is detonated, but suffers from the disadvantage that a gas tube must be provided, which extends, for instance, along the underside of the barrel, adding to the weight and bulk of the arm, and the additional disadvantage of disturbance of the barrel as the bullet passes the port in the barrel. Further, the operating gas pressure derived even from a port located near the mouth of the barrel is not as low as is desirable, and the unlocking of the bolt in certain conventional gas-operated firearms of the prior art starts to take place while the bullet is still in the barrel, and the operating gas pressure is very high as compared with the ambient pressure. This premature unlocking or at least partial unlocking of the bolt during the existence of relatively high operating gas pressure sometimes leads to the jamming of said conventional gas-operated firearms by distorted cartridge cases, which are "ballooned" against the face of the retreating bolt by the remaining high-pressure operating gas.